山地流域における土砂流出 ―土砂濃度と粒径特性―

Abstract

The authors have been observing the sediment yield in a mountain stream, HirudaniExperimental Watershed, at Hodaka Sedimentation Observatory.Present year, a more reliable facilities was used for picking considerably coarse gravelscontained in running water. Therefore following facts were proved:1. Sediment concentration decreases even while water discharge is constant after thepeak discharge.2. In some cases, the maximum size of sediments which is caught happenes fairlybefore and after the peak of sediment concentration are attained.3. The maximum of sediment concentration in a flood is likely to depend on theratio of peak discharge to base flow or the increasing rate of discharge than on the peakdischarge itself of the flood.